Effect of Physical and Social Components of Enriched Environment on Astrocytes Proliferation in Rats After Cerebral Ischemia/Reperfusion Injury

Treatment of enriched environment (EE) exerts neuroprotective effect in cerebral ischemia/reperfusion (I/R) injury. However, how the component of EE contributes to the functional recovery after brain ischemia remains unclear. Here we examined the effect of physical and social components of EE on poststroke astrocytes proliferation using an animal model of middle cerebral artery occlusion (MCAO) followed by reperfusion. Rats were divided into five groups: physical enrichment group (PE), social enrichment group (SE), physical and social enrichment group (PSE), ischemia + standard group (IS) and sham-operated + standard group (SS). In a set of behavioral tests, we demonstrated that animals in the enriched groups exhibited improved functional outcomes compared with those in standard group. Reduced infarct volume was only observed in PSE and PE groups. Double immunofluorescent labeling and western blot analysis revealed that rats in PSE and PE groups showed significantly more proliferated astrocytes and higher expression levels of brain-derived neurotrophic factor (BDNF) in the periinfarct cortex, compared with those in SE group. Astrocytes proliferation and BDNF expression were significantly correlated with functional outcomes. Collectively, this study suggests that physical activity is a more important component of EE regarding the effect on astrocytes proliferation and BDNF expression, which may contribute to the improved neurological function of stroke animals.